One
of the most spectacular sights in the world of birds is a
kill of another bird by a stooping Peregrine Falcon. The
falcon plunges steeply downward, wings partially closed, at
speeds that can exceed 150 miles an hour. It was long
thought that falcons and other raptors struck with their
feet clenched like a fist. High-speed cinematographic
studies, however, have shown that they strike their prey
from above with all four toes fully extended. The
Peregrine's victim is often ripped by the falcon's talons,
producing a shower of feathers. Usually the prey is picked
up off the ground afterward, although occasionally the
falcon will stoop again and gather the tumbling bird before
it falls to the ground.

Peregrines use other modes
of hunting as well, sometimes diving past their prey and
then zooming up from beneath to snatch it from behind and
below, or simply catching a small bird from above with their
talons. Sometimes they will patrol low over the ground like
a harrier, attempting to flush game birds. The hunting
success of Peregrines can vary widely with location, season,
and even sex, as Cornell ornithologist Tom Cade showed with
an interesting comparison. One breeding male in the eastern
United States, hunting Blue jays almost exclusively, caught
93 percent of his targets one season. A breeding female in
Australia was successful only 31 percent of the time, but
she captured mostly coots which were more than five times as
heavy as the Blue jays. Considering that the female probably
weighed half again as much as the male, and analyzing the
energy costs and benefits of both hunting patterns, Cade
concluded that it took the male 49 kilocalories (kcal, what
dieters normally just call a "calorie") to deliver 1,000
kcal of prey to the eyrie, while the female expended just 43
kcal to get the same job done. The female is more efficient,
but is limited in the amount of time she can hunt because of
her nest guarding duties. The somewhat less-efficient male
probably delivered more nourishment to the young because he
could spend more time hunting.

As a group, raptors exhibit
an extraordinary variety of hunting techniques. Aside from
owls (which are sometimes considered raptors) almost all are
diurnal hunters, but a few like the European Hobby (a
smaller relative of the Peregrine) will pounce on mice in
the moonlight. Some are like the Peregrine in that they hunt
at high speed. The Sharp-shinned Hawk, for example, often
flashes through relatively thick woodland, maneuvering
skillfully and often snatching passerines right from their
perches. Others, like American Kestrels, Black-shouldered
Kites, and the young of the very successful Red-tailed Hawk,
often hover when hunting, and then drop steeply down on
their targets. And still others, including adult Red-tails,
soar as they watch for prey on the ground. But most hunting
by raptors probably is done from perches with a commanding
view from which the bird can scan the surrounding terrain
with its telescope-like vision, where it can glide rapidly
to gather in its prey. Interestingly, whether an American
Kestrel hovers or perch-hunts depends in large part on
whether there is a good breeze to hover in. Whichever
technique is used, most prey of raptors are killed by the
talons of the contracting foot being driven into their
bodies; if required, the hooked bill is used to give a
coup-de-grace. The exceptions are falcons, which ordinarily
kill by biting into the necks of victims not dispatched in
mid-air. (Owls also bite the necks of their
prey.)

A Merlin
stoops on an Inca Dove, killing it with a slashing
blow of its open feet

Of course, there are some
birds of prey (in addition to falcons) that employ rather
specialized hunting techniques. Perched or hovering Ospreys
plunge into water to grab living fish; Snail and Hook-billed
Kites course around like harriers in pursuit of their
less-than-agile preferred food: snails.